Fully conjugated coil-like polymer poly-(3-hexylthiophene) (P3HT) and aromatic
heterocyclic copolymer poly[2,6-(4,4-bis(2-ethylhexyl)-4H-cyclopenta-[2,1-b;3,4-b¡¬]-
dithiophene)-alt-4,7-(2,1,3-benzothiadiazole] (PCPDTBT) were applied separately as
donors mixed with derivatized carbon fullerence [6,6]-phenyl C61-butyric acid methyl
ester (PC61BM) serving as an acceptor. Single layer photovoltaic cells of ITO/
PEDOT:PSS/polymer:PC61BM/LiF/Al were fabricated to study photovoltaic effect of
layer thickness, thermal annealing, composition variance, and processing solvent.
At a P3HT:PC61BM weight ratio of 1:1, the thermally annealed photovoltaic cells
achieved a conversion efficiency (£bp) of 4.58 % from enhanced contact between cathode
and active layer. At a PCPDTBT:PC61BM weight ratio of 1:1.25, the best £bp was 2.62
%. The efficiency difference was due to PCPDTBT:PC61BM was highly phase
separated preventing the formation of conductive interpenetrating network to facilitate
charge transport. Its device fill factor was limited to be 38 %. Under the same spin
coating speed, solutions of different PC61BM concentration would yield different spun
film thickness leading to large change in conversion efficiency (£bp). At a constant
active layer thickness, £bp tended to be stable indicating that £bp was affected more by
the layer thickness than by PC61BM concentration. A layer of mixing P3HT:
PCPDTBT: PC61BM would expand the absorption range from visible to near infrared.
However, an increased PCPDTBT concentration did not help £bp. This is due to charge
transport imbalance between P3HT and PCPDTBT leading to an £bp less than those of
individual blends with PC61BM. Device £bp was consistently higher for using a
solvent with a boiling point higher than polymer glass transition temperature (Tg).
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0120111-143514 |
| Date | 20 January 2011 |
| Creators | Lin, Tzu-chin |
| Contributors | Ming Chen, Shih-Jung Bai, Jen-Wei Huang, Bae-Heng Tseng |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | Cholon |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0120111-143514 |
| Rights | not_available, Copyright information available at source archive |
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